Prior art flexible walled bottles, which are manually deformable to decrease their inner volumes so as to force out the contents thereof, are known as squeeze-bottles. When the deformed bottle wall is released, it is designed to be self-restoring to its undeformed condition. As the bottle is emptied of its fluid, air is drawn into the bottle to replace the fluid. The fluid being dispensed is typically incompressible and heavier than air. When the bottle is set upright on its base, the fluid flows to the bottom of the bottle. If a nearly empty squeeze-bottle remains substantially upright, no fluid is dispensed when it is squeezed, since air is first pumped out and then sucked back into the bottle. If the same bottle is inverted, and the fluid is resistant to flow, the fluid remains inaccessible until it has had time to flow from the bottom of the bottle to substantially block the bottle's discharge opening. Only then does squeezing the bottle compress air behind the fluid and force it out of the discharge opening. The wait may be quite inconvenient, especially when fluids resistant to flow are residing in nearly empty, tall bottles. In extreme cases, gravity alone does not enable such a fluid to flow to the discharge opening in the bottle.
Consequently, consumers have recognized the need for an "always ready to dispense" squeeze-bottle for flow resistant fluids. One known means for satisfying that need involves the addition of a collapsible fluid-containing bag inside a squeeze-bottle. Streck U.S. Pat. No. 4,865,224 and Uhlig U.S. Pat. No. 4,098,434 disclose such structures. When a fluid-containing bag is sealingly secured to the discharge end of such a squeeze-bottle, air is trapped between the inside of the squeeze-bottle and the outside of the bag. This air is compressed when the bottle is subsequently squeezed. Air pressure is thereby transmitted to the bag, causing the bag to discharge its fluid. Compression of the air trapped between the inside of the squeeze bottle and the outside of the bag can be accomplished by blocking a vent hole in the squeeze bottle with a finger or by providing the squeeze bottle with a one-way vent valve.
When a bag-in-squeeze-bottle dispenser functions properly, successive squeezes of the bottle cause the bag inside to collapse around the decreasing volume of fluid remaining in the bag. However, the "always ready to dispense" benefit is not automatically realized in prior art bag-in-squeeze-bottle dispensers unless the bag is prevented from collapsing upon itself near the discharge opening. Unless means are provided to prevent the premature choking off of fluid flow, not only will the "always ready to dispense" benefit be lost, but a significant volume of fluid will remain completely inaccessible within the bag. This causes the consumer to either waster the fluid product remaining within the dispenser or go to the trouble of manually breaking the package open to access the fluid product remaining therein. Neither of these alternatives are acceptable to most consumers.
Although it is believed that air pressure developed around the outside of the flexible bag by squeezing of the outer container is uniformly distributed in prior art bag-in-squeeze-bottle packages, it has been observed that, if left unsecured to the outer container, the flexible bag tends to first collapse on itself at its discharge end regardless of the dispenser's orientation. When the bottle is inverted, the unconstrained bag is free to slump toward the discharge end where its folds may further aggravate this fluid flow choking problem. Accordingly, one object of the present invention is to prevent the collapse of a fluid-containing bag in a squeeze-bottle in order to avoid disruption of fluid discharge until substantially all of the fluid has been dispensed from the bag.
Prior art attempts to solve this problem have involved securement of the bottom end of the bag to the bottom end of the container to force the bag to collapse in an inwardly radial direction. However, solutions of this type have proven difficult to implement. In addition, they have not proved completely effective, since the uppermost portion of the bag may still prematurely collapse and prevent fluid product in the lowermost portions of the bag from reaching the bag's discharge orifice.
Another means of preventing such premature collapse of the fluid-containing bag is by securing the bag to the inner sidewall of a squeeze-bottle approximately midway along the longitudinal axis of the bottle. Such constraint is intended to cause the bag to collapse in a predictable fashion, i.e., the bag inverts substantially about its mid-point securement and thereby avoids the fluid choking problem.
Harrison U.S. Pat. No. 2,608,320 discloses a squeezable container having a cylindrical bag cartridge consisting of both a flexible lower cylinder half and a rigid upper cylinder half. The discharge end of the dispenser is at the upper end of the rigid half. The fluid-containing bag requires connection to the lowermost end of the rigid portion of the container. This design provides controlled bag collapse by inversion of the flexible portion of the bag into the rigid portion of the container.
One difficulty associated with squeeze bottles employing such invertible bags is that it may be difficult to readily gain the access needed to secure the flexible bag and the outer container to one another at the desired predetermined points. To provide suitable access for the sealing tools may negatively impact dispenser production speeds or impose design limitations on the shape of the dispenser.
Another difficulty with squeeze bottles employing such invertible bags is that when a bag inverts axially upward relative to the base of the container, the uppermost end of the container becomes heavier, thereby requiring a relatively wide base to maintain stability against tipping toward the end of the dispenser's life cycle. This factor tends to limit design flexibility in terms of the shape of the outer container.
Accordingly, it is another object of the present invention to provide a bag-in-squeeze-bottle fluid dispenser which can be reliably manufactured and filled at high speed and which overcomes many of the aforementioned problems and/or design limitations inherent in prior art bag-in-squeeze-bottle dispensers.